Dental patient's chairs come in a variety of types, styles, and sizes. Traditional dental patients' chairs are adjustable, typically by means of a simple pivot between the seat and the backrest which allows for simple articulation of the back as it rotates about the pivot. Such traditional chairs are, however, problematic for a number of reasons. First, it is typically important that the patient's head does not move relative to the headrest. Any time movement of a traditional dental chair is desired, the backrest pivots about an axis common to the seat. Upon pivoting the backrest, a person typically must move anywhere from a few to several inches in the chair in order to be seated squarely on the seat cushion with the backrest in the proper supporting position. Necessarily, the position of the patient's head relative to the headrest will change. This requires the treating physician to readjust the headrest.
Further, with respect to the patient's head, the patient's jaw and skull relative to the patient's backbone must be oriented in an optimal position for the dentist, oral surgeon or other treating physician to access the areas of the mouth. If the head and jaw move relative to the patient's backbone during adjustment of the chair, the patient may not be able to open his or her mouth sufficiently or there may be some other impediment to accessing the mouth areas.
A primary problem with respect to traditional dental patients' chairs is that the pivot axis, particularly a simple pivot between the backrest and the seat, is not coincident with the axis of the human body "pivot." Therefore, the person's body and the seat when articulating will not remain in constant, identical contact with one another. One attempt to solve this problem has been to try to locate the axis of the chair pivot close to the axis that is assumed to be where rotation of the upper torso takes place relative to the lower body. This, however, creates two problems. First, this would require a large hinge mechanism on the chair well above the seat cushion level that would get in the way of the patient getting in and out of the chair.
Perhaps more importantly, the human body does not pivot like a simple hinge. Rather, the human body has one hinge between the upper legs and the pelvic bone, and a second hinge between the lower part of the backbone and that same pelvic bone. This creates a complex hinge mechanism that must be dealt with in a sophisticated way.
An overriding consideration in today's medical profession, including the dental profession, is contamination. With the ever-increasing presence of serious diseases, such as AIDS, hepatitis, and the like, contamination has become particularly important. A major problem with respect to any dental patient's chair is the need for the treating physician to adjust the chair manually. For example, the physician is typically required to manipulate a variety of manually controlled switches or buttons, such as to adjust the headrest, backrest, or even the light used in treating the patient. Each time such an adjustment is required, the treating physician must put down the instruments, and readjust the particular piece of equipment. Any contamination on the treating physician's gloves will contaminate any of these various manually operated adjustments. These same adjustments are those that are typically not thought of when sterilization takes place between patients, as compared to the physician's instruments and the like.
Another important consideration is the patient's comfort and sense of security. The patient should not feel that he or she is sliding up and down in the seat in an uncontrolled manner, particularly where critical angles of inclination are involved. This occurs when a simple pivot, described above, is used in a patient's chair.
Some attempts have been made to place a sliding mechanism in the backrest portion of a chair to allow for the back to move when the seat is being reclined. Once again, however, this does not recognize the complex pivot that occurs in the human body. In addition, any mechanisms added to the backrest of the chair will create an impediment to the doctor performing work on the patient. In designing a dental patient's chair, the backrest should be kept as thin as possible so the doctor can have maximum patient positioning freedom while keeping his knees and legs free to get close to his patient.
There is a need, therefore, to provide a dental patient's chair that can be completely and fully manipulated without the need of the treating physician to touch any part of the chair with his or her hands. There is a further need to develop a dental patient's chair that pivots in the same complex manner as the human body so that when the chair is reclined, the human body will follow both the backrest and the seat in the exact same manner. This would eliminate any need for the patient to readjust him or herself in the chair, and would maintain the head in the relatively same position on the headrest.
The present invention relates to a dental patient's chair that is fully and completely adjustable by the use of a unique foot control system that eliminates the need to manipulate any hand-operated control knobs or levers. The present invention also involves a sophisticated linkage assembly which allows the seat to pivot and move in the same manner as the human body when the human body articulates about the complex pivot created at the pelvic bone, the upper legs, and the lower part of the backbone. This allows the patient's body to remain in the same position relative to the backrest and the seat of the patient's chair as the chair is articulated in a variety of positions. Other advantages, features, and objects of the invention will become more apparent from the detailed description of the invention that follows.